Coolant for propellant actuated gas generator



June 2, 1970 A. M. HALSTEAD ETAL 3,515,518

I COOLANT FOR PROPELLANT ACTUATED GAS GENERATOR Filed Aug. 23, 1967INVENTORS. ARTHUR M. HALSTEAD, DECEASED BY ALBERTAMHALSTEAQADMINISTRATRIX OSYP NIMYLOW CZ BY 7n a Q '1 f g 'z I ATORNYSUnited States Patent Office US. Cl. 23-281 4 Claims ABSTRACT OF THEDISCLOSURE A propellant actuated gas generator having a metalliccarbonyl coolant such as molybdenum-hexacarbonyl in a forward chamberand surrounding a dispersing tube for developing substantially permanentor sustaining gas pressure for inflating purposes. A first filter bed ispositioned in the rearward chamber forward of the propellant and asecond filter bed is located in the forward chamber forwardly of themetallic carbonyl coolant.

This invention relates to gas generators and, more particularly is a gasgenerator capable of developing pressure for inflating purposes.

In propellant actuated gas generators for inflating tanks, life rafts,etc., coolants heretofore employed such as salts of ammonium oftencontain water of crystallization. Upon heating they partially sublimeand partially decompose endothermically to ammonia gas, carbon dioxidegas and water vapor, both gases being soluble in water. During initialinflation, the gases fill the tank, but only establish a temporarypressure prior to being cooled to ambient temperature whereupon thesublimed coolant solidifies, and along with the gases dissolve in theexisting water condensation, all of which adversely results in aconsiderably reduced tank or vessel pressure.

Accordingly, one of the objects of the invention is to provide aneflicient gas generator capable of developing substantially permanent orsustaining gas pressure for inflating purposes.

Another object is to use in a gas generator a coolant which uponendothermic decomposition provides a permanent gas which is not solublein water.

These and other objects, features and advantages will become moreapparent from the following description and accompanying drawing whichis a longitudinal sectional view of a preferred gas generatingarrangement embodying the principles of the invention.

In the drawing the propellant actuated gas generator has a substantiallyhollow, cylindrical main body 11 with a laterally extending partitioningwall 12 positioned substantially mid-length thereof and defining arearward chamber 13 containing a predetermined form of low temperature,slow burning propellant 14 and a charcoal filter bed 15 positionedforwardly of the propellant and adjacent the wall 12, as well as aforward chamber 16 that contains a preferred form of coolant 17 and asecond filter bed 18 of aluminum oxide stones adjacent the forward endwall 19. Wall 19 has an appropriately apertured central protrusion 20defining an exit port that suitably connects with a tank or otherinflatable vessel 21 such as a life raft. The generator rearward endwall 22 has a central threaded opening 23 to receive a suitableattachment portion of an ignition element 24 that when appropriatelyactuated will ignite the propellant 14.

Partitioning wall 12 has a central fluid communicating aperture 25 theforward end of which is suitably threaded 3,515,518 Patented June 2,1970 to mount a hollow dispersing tube 26 which is substantially closedexcept for a rear inlet port and a plurality of exit ports 27distributed in predetermined spaced relationship throughout its side andforward walls.

Hot pressure gas (at approximately 2000 F.) developed upon propellantignition passes through filter bed 15 prior to being blown into thesurrounding coolant material 17 by dispersing tube 26. The coolantmaterial, to be more fully described, is heated to a decompositiontemperature of approximately 300 F. and gas products of the propellant14 and coolant 17 are filtered through filter bed 18 prior to beingdelivered to the inflatable device 21 via the generator outlet port.

A preferred coolant in the form of a metallic carbonyl, such asmolybdenum-hexacarbonyl Mo(CO) composition, decomposes endothermicallyat about 300 F. into a metallic solid and carbon monoxide gas, thelatter being a permanent gas not soluble in water. The gas products ofthe decomposed metallic carbonyl coolant substantia ly eliminate anyharmful water contribution the generator gas output, and as a result,when the gas generator delivers a predetermined pressure gas to theinflatable device, the delivered will substantially maintain the desiredpressure even after cooling to ambient temperature.

It is contemplated that other metallic carbonyls, such as cobalt tetracarbonyl Co (CO) and iron nona carbonyl Fe (CO) can be satisfactorilyemployed to produce the desired coolant effect and sustaining gaspressure for inflating purposes.

For substantially similar test conditions for coolants in propellantactuated gas generating arrangements, the following comparative averagetest data was obtained for molybdenum hexacarbonyl coolant relative to aprevioulsy known ammonium carbonate coolant.

Molybdenum carbonyl Max. raft pressure (at inflation)- 8.8 p.si.l.g).(23.5)

p.s. .a. Raft pressure at inflation plus 3.5 p.s.Lg. (18.2

30 min. p.s.i.a.).

Ammonium carbonate 8.9 p.s.Lg. (23.6

p.s.i.a.).

1.7 p.s.i.g. (16.4

p.s.i.a.).

77.5% retained 69.5% retained It should be noted that the 18.2 p.s.i.a.of the molybdenum carbonyl pressure will satisfactorily maintain thedesired inflation, whereas the 16.4 p.s.i.a. of the ammonium carbonatedeveloped pressure will barely satisfy the desired requirements.

Various modifications, changes or alterations may be resorted to withoutdeparting from the scope of the invention as defined in the appendedclaims.

We claim:

1. In a propellant gas generator having a substantially hollow main bodywith a laterally extending partitioning wall positioned substantiallymid-length of said main body and defining forward and rearward chamberstherein said wall having a central aperture therethrough,

a slow burning propellant in said rearward chamber,

a dispersing tube in said forward chamber in fluid communication withsaid rearward chamber and having a plurlaity of apertures, and

a metallic carbonyl composition in said forward chamber and surroundingsaid dispersing tube.

2. The gas generator of claim 1 wherein a filter bed is positioned insaid rearward chamber forwardly of said propellant, and a second filterbed in said forward chamber forwardly of said metallic carbonylcomposition.

3. The gas generator of claim 2 in which said metallic carbonyl ismolybdenum-hexacarbonyl.

carbonyl.

4. The gas generator in accordance with claim 1 wherein said metalliccarbonyl is molybdenum-hexa- References Cited UNITED STATES PATENTSMillns 10239 Maurice et a1. 10239 White et a1. 23-281 Hebenstreit et a1.23-281 XR Kowalick et a1. 23 2s1 1 4 OTHER REFERENCES 5 MORRIS O. WOLK,Primary Examiner D. G. MILLMAN, Assistant Examiner US Cl. X.R.

